How do you survive a gunshot wound?

In the wake of the horrific Aurora, Colo., tragedy, 58 people survived the shooting incident.

The details of the survivors' injuries remain unknown, and some remain in critical condition. Reports tell of survivors who suffered gunshot wounds to the neck, abdomen, brain, throat and legs.

Over the last 20 years, the chances that a person will survive acritical gunshot woundhave increased substantially, perhaps by around 30 to 40 percent, said Dr. Thomas Scalea, professor of surgery at the University of Maryland Medical Center's R Adams Cowley Shock Trauma Center, who has treated thousands of patients with gunshot wounds over his three-decade career.

The most important factors, in terms of a person's survival odds, are the location of the injury, the amount of blood lost and how quickly the victim is transported to the hospital, said Scalea, who is not involved in the care of the Aurora shooting victims.

Being shot in the trunk or torso is more life-threatening than being shot in an extremity, Scalea said.

And within major organs such as the heart or liver, some injuries are more serious than others because they cause more bleeding, Scalea said.

For example, being shot in the left side of theheartgenerally causes more bleeding than being shot on right side of the heart, because the right side has lower blood pressure, Scalea said. An injury to more than one of the heart's four chambers causes more bleeding than an injury to only one chamber, and a wound that goes through the septum — which separates the heart's left and right sides — is worse than an injury that does not go through the septum, Scalea said.

With gunshot wounds that involve the liver, an injury to the organ's center causes more bleeding than an injury to its periphery, and a wound on the right side is worse than the left, Scalea said.

The main concern with gunshot wounds that involve the intestine or stomach is not bleeding, butinfections that result from spillage of the contents of those organs, Scalea said.

Both technical advances and changes in trauma practice have led to an increase in the percentage of people who survive gunshot wounds, Scalea said.

Rather than trying to stabilize victims in the field, health care personnel now try to get injured people into a transport vehicle and to a hospital as soon as possible, Scalea said.

Doctors use more rapid tests, such as ultrasounds, to diagnosis hemorrhages, or internal bleeding, Scalea said. And they have alternative ways to stop bleeding besides open surgery, such as using of catheters under X-ray guidance, he said.

Finally, when surgery is performed, instead of doing one major operation to treat a gunshot victim, doctors now tend to perform damage control. They treat the most critical injury first, and go back to treat less life-threatening injuries with later operations, Scalea said. Performing several shorter surgeries, rather than a long operation, is usually better tolerated by the patient, and can mean the victim loses less fluid and blood at one time, he said.

While people can, theoretically, survive a gunshot wound to any part of their body, the chances of survival vary on a case by case basis, he said.